Intraoperative diagnostic procedures are considered of fundamental importance in surgery. They may augment the findings of previous exams and often yield information not procurable by other means. Surgical management of the patient can thus be improved through such procedures by providing the information necessary to plan, modify, or evaluate a surgical intervention.
Past methods and devices for acquiring intraoperative vascular data have a number of shortcomings. Relatively large hand-held ultrasonic imaging probes have been available but their hand-held design and overall dimensions make them difficult to maneuver within the thoracic cavity. Their size and design therefore limits the extent of examination that can be performed. Also, such hand-held imagers often utilize a mechanical means for sector scanning, resulting in mechanical vibrations of the instrument that may have the potential of embolizing intravascular plaque and thrombi in addition to the possibility of damaging suture integrity. In general, such probes are expensive, non-disposable, and provide little tactile feedback to the operator.
Similarly, present methods of intraoperative blood flow measurement possess their share of disadvantages. Intraoperative flow velocity estimation techniques are limited in their range of applications and the instruments are difficult to position properly, require intensive operator interaction, and in many situations yield inaccurate results.
Accordingly, a main aspect of this invention lies in providing a relatively small, disposable, finger-mounted device for facilitating the intraoperative evaluation of vascular morphology and blood flow characteristics. The finger-mounted probe is combinable with a conventional, miniaturized, ultrasound imaging catheter and, in a preferred embodiment, provides both two-dimensional ultrasonic imaging and Doppler blood flow indications. Using the device, a surgeon may collect comprehensive anatomic and hemodynamic information of selected vascular segments simply by touching the surface of interest with his/her fingertip. In such a manner, diagnostic vascular information may be acquired from virtually any site in the surgical field that the surgeon's fingers can reach.
The probe, being separable from the imaging catheter, may be fabricated inexpensively enough for one-time use. Because of its construction, size, and finger attachment, it provides tactile feedback throughout an examination procedure. Although the probe may be used with a conventional intravascular imaging catheter, such catheter is used in an extravascular, not intravascular manner.
Briefly, the probe includes an elongated, channel-shaped body formed of relatively rigid, non-echogenic material that is substantially transparent to ultrasonic energy. The body has a smoothly-curved lower surface and an upper surface of concave cross sectional contour dimensioned to receive the underside of a user's finger, preferably the index finger. An integral band bridges the body and serves as retaining means for holding the probe on a surgeon's finger. An elongated chamber extends inwardly from the body's proximal end along the longitudinal midline thereof and removably receives the distal segment of an ultrasound 2-D-echo mode imaging catheter having an ultrasonic transducer with an imaging plane normal to such longitudinal midline for emitting ultrasonic pulses and for receiving and transmitting ultrasonic reflections. Ideally, the imaging plane is aligned with the retention band that extends over the tip of a user's finger and provides a visual aid to the user in positioning the probe in relation to the vascular area of evaluation. A Doppler generator/detector is preferably mounted in the distal end of the body and is directed towards the imaging plane of the ultrasound catheter for directing, detecting, and transmitting signals representative of blood flow velocity through a vessel contacted by the smooth undersurface of the probe.
Aqueous fluid such as sterile saline is introduced into the chamber to surround the imaging catheter and provide an acoustic couple between the catheter and the probe. Irrigation ports leading from the chamber to the underside of the probe, and also from the chamber to the probe's upper surface, allow small amounts of the fluid to escape from the chamber and provide an acoustic couple between the user's finger, the probe, and the surface under investigation.
In one embodiment, the catheter-receiving chamber of the probe is lined with a tubular hydrogel liner. In its unhydrated state the liner defines a passage considerably larger in cross section than that of a catheter to be received therein, thereby facilitating catheter insertion when the parts are being assembled for use. Hydration of the hydrogel liner by sterile saline introduced into the chamber causes a swelling of the liner which in turn fills the voids, eliminates air pockets, secures the catheter in place, and provides an acoustic couple between the catheter and the probe.
Other features, advantages, and objects will be apparent from the specification and drawings.